1. Field
The following description relates to an actuator, and more particularly, to an ElectroActive Polymer (EAP) actuator and a method of manufacturing the same.
2. Description of the Related Art
An actuator is a power processing device for a remote operation or an automatic control using power. The actuator needs to have a superior durability against frequent uses, high reliability, accuracy of control, good controllability, rapid response, etc. Actuators can be distinguished into types such as hydraulic actuators, pneumatic actuators, electromagnetic motors, shape memory alloys, micro-motors, and ElectroActive Polymer (EAP) actuators.
In recent years, the EAP actuator has gained a large amount of interest. EAP generally refers to polymers whose shape is modified by electric stimulation, and EAP may widely refer to polymers whose shape is modified by chemical stimulation or thermal stimulation in addition to an electric stimulation. The EAP includes types of Ionic Polymer Metal Composites (IPMC), dielectric elastomers, conducting polymers, polymer gels, Polyvinylidene Fluoride resins, carbon nanotubes, shape memory polymers, etc. The EAP actuator is used in various application devices such as micro cameras, polymer Micro Electro Mechanical Systems (MEMS), bio systems, energy harvesting, etc.
Since the EAP actuator has a great mechanical resistance, even a small sized EAP actuator has a relatively large displacement and high generative force in conjunction with the large displacement. For example, the EAP actuator may be used as a driving actuator for a varifocal fluidic lens which is included in a high performance image pick up device in a small sized and thin mobile electronic device. The varifocal fluidic lens is used to implement various functions such as Auto-Focus (AF) function, a zoom function, an Optical Image Stabilization (OIS) function, etc.
However, in order to obtain a high driving force capable of producing a great displacement, a driving voltage needs to be several hundred volts or above. However, a conventional EAP actuator using such a high driving voltage has limited applications in certain devices, such as mobile electronic devices, which operate on relatively low driving voltages, for example 24V or below. In order to reduce the required driving voltage in the actuator, a multilayer EAP polymer actuator has been proposed. The multilayer EAP polymer actuator has a structure in which a plurality of thin polymer layers are stacked up on top of each other while alternately interposing driving electrodes that have different electric potentials therebetween.